/**!
 * Sortable
 * @author	RubaXa   <trash@rubaxa.org>
 * @author	owenm    <owen23355@gmail.com>
 * @license MIT
 */

(function sortableModule(factory) {
  "use strict";

  if (typeof define === "function" && define.amd) {
    define(factory);
  }
  else if (typeof module != "undefined" && typeof module.exports != "undefined") {
    module.exports = factory();
  }
  else {
    /* jshint sub:true */
    window["Sortable"] = factory();
  }
})(function sortableFactory() {
  "use strict";

  if (typeof window === "undefined" || !window.document) {
    return function sortableError() {
      throw new Error("Sortable.js requires a window with a document");
    };
  }

  var dragEl,
      parentEl,
      ghostEl,
      cloneEl,
      rootEl,
      nextEl,
      lastDownEl,

      scrollEl,
      scrollParentEl,
      scrollCustomFn,

      oldIndex,
      newIndex,

      activeGroup,
      putSortable,

      autoScrolls = [],
      scrolling = false,

      awaitingDragStarted = false,
      ignoreNextClick = false,
      sortables = [],

      pointerElemChangedInterval,
      lastPointerElemX,
      lastPointerElemY,

      tapEvt,
      touchEvt,

      moved,


      lastTarget,
      lastDirection,
      pastFirstInvertThresh = false,
      isCircumstantialInvert = false,
      lastMode, // 'swap' or 'insert'

      targetMoveDistance,


      forRepaintDummy,
      realDragElRect, // dragEl rect after current animation

      /** @const */
      R_SPACE = /\s+/g,

      expando = 'Sortable' + (new Date).getTime(),

      win = window,
      document = win.document,
      parseInt = win.parseInt,
      setTimeout = win.setTimeout,

      $ = win.jQuery || win.Zepto,
      Polymer = win.Polymer,

      captureMode = {
        capture: false,
        passive: false
      },

      IE11OrLess = !!navigator.userAgent.match(/(?:Trident.*rv[ :]?11\.|msie|iemobile)/i),
      Edge = !!navigator.userAgent.match(/Edge/i),
      // FireFox = !!navigator.userAgent.match(/firefox/i),

      CSSFloatProperty = Edge || IE11OrLess ? 'cssFloat' : 'float',

      // This will not pass for IE9, because IE9 DnD only works on anchors
      supportDraggable = ('draggable' in document.createElement('div')),

      supportCssPointerEvents = (function() {
        // false when <= IE11
        if (IE11OrLess) {
          return false;
        }
        var el = document.createElement('x');
        el.style.cssText = 'pointer-events:auto';
        return el.style.pointerEvents === 'auto';
      })(),

      _silent = false,
      _alignedSilent = false,

      abs = Math.abs,
      min = Math.min,

      savedInputChecked = [],

      _detectDirection = function(el, options) {
        var elCSS = _css(el),
            elWidth = parseInt(elCSS.width),
            child1 = _getChild(el, 0, options),
            child2 = _getChild(el, 1, options),
            firstChildCSS = child1 && _css(child1),
            secondChildCSS = child2 && _css(child2),
            firstChildWidth = firstChildCSS && parseInt(firstChildCSS.marginLeft) + parseInt(firstChildCSS.marginRight) + _getRect(child1).width,
            secondChildWidth = secondChildCSS && parseInt(secondChildCSS.marginLeft) + parseInt(secondChildCSS.marginRight) + _getRect(child2).width;
        if (elCSS.display === 'flex') {
          return elCSS.flexDirection === 'column' || elCSS.flexDirection === 'column-reverse'
              ? 'vertical' : 'horizontal';
        }
        if (child1 && firstChildCSS.float !== 'none') {
          var touchingSideChild2 = firstChildCSS.float === 'left' ? 'left' : 'right';

          return child2 && (secondChildCSS.clear === 'both' || secondChildCSS.clear === touchingSideChild2) ?
              'vertical' : 'horizontal';
        }
        return (child1 &&
            (
                firstChildCSS.display === 'block' ||
                firstChildCSS.display === 'flex' ||
                firstChildCSS.display === 'table' ||
                firstChildCSS.display === 'grid' ||
                firstChildWidth >= elWidth &&
                elCSS[CSSFloatProperty] === 'none' ||
                child2 &&
                elCSS[CSSFloatProperty] === 'none' &&
                firstChildWidth + secondChildWidth > elWidth
            ) ?
                'vertical' : 'horizontal'
        );
      },

      /**
       * Detects first nearest empty sortable to X and Y position using emptyInsertThreshold.
       * @param  {Number} x      X position
       * @param  {Number} y      Y position
       * @return {HTMLElement}   Element of the first found nearest Sortable
       */
      _detectNearestEmptySortable = function(x, y) {
        for (var i = 0; i < sortables.length; i++) {
          if (sortables[i].children.length) continue;

          var rect = _getRect(sortables[i]),
              threshold = sortables[i][expando].options.emptyInsertThreshold,
              insideHorizontally = x >= (rect.left - threshold) && x <= (rect.right + threshold),
              insideVertically = y >= (rect.top - threshold) && y <= (rect.bottom + threshold);

          if (insideHorizontally && insideVertically) {
            return sortables[i];
          }
        }
      },

      _isClientInRowColumn = function(x, y, el, axis, options) {
        var targetRect = _getRect(el),
            targetS1Opp = axis === 'vertical' ? targetRect.left : targetRect.top,
            targetS2Opp = axis === 'vertical' ? targetRect.right : targetRect.bottom,
            mouseOnOppAxis = axis === 'vertical' ? x : y;

        return targetS1Opp < mouseOnOppAxis && mouseOnOppAxis < targetS2Opp;
      },

      _isElInRowColumn = function(el1, el2, axis) {
        var el1Rect = el1 === dragEl && realDragElRect || _getRect(el1),
            el2Rect = el2 === dragEl && realDragElRect || _getRect(el2),
            el1S1Opp = axis === 'vertical' ? el1Rect.left : el1Rect.top,
            el1S2Opp = axis === 'vertical' ? el1Rect.right : el1Rect.bottom,
            el1OppLength = axis === 'vertical' ? el1Rect.width : el1Rect.height,
            el2S1Opp = axis === 'vertical' ? el2Rect.left : el2Rect.top,
            el2S2Opp = axis === 'vertical' ? el2Rect.right : el2Rect.bottom,
            el2OppLength = axis === 'vertical' ? el2Rect.width : el2Rect.height;

        return (
            el1S1Opp === el2S1Opp ||
            el1S2Opp === el2S2Opp ||
            (el1S1Opp + el1OppLength / 2) === (el2S1Opp + el2OppLength / 2)
        );
      },

      _getParentAutoScrollElement = function(el, includeSelf) {
        // skip to window
        if (!el || !el.getBoundingClientRect) return win;

        var elem = el;
        var gotSelf = false;
        do {
          // we don't need to get elem css if it isn't even overflowing in the first place (performance)
          if (elem.clientWidth < elem.scrollWidth || elem.clientHeight < elem.scrollHeight) {
            var elemCSS = _css(elem);
            if (
                elem.clientWidth < elem.scrollWidth && (elemCSS.overflowX == 'auto' || elemCSS.overflowX == 'scroll') ||
                elem.clientHeight < elem.scrollHeight && (elemCSS.overflowY == 'auto' || elemCSS.overflowY == 'scroll')
            ) {
              if (!elem || !elem.getBoundingClientRect || elem === document.body) return win;

              if (gotSelf || includeSelf) return elem;
              gotSelf = true;
            }
          }
          /* jshint boss:true */
        } while (elem = elem.parentNode);

        return win;
      },

      _autoScroll = _throttle(function (/**Event*/evt, /**Object*/options, /**HTMLElement*/rootEl, /**Boolean*/isFallback) {
        // Bug: https://bugzilla.mozilla.org/show_bug.cgi?id=505521
        if (options.scroll) {
          var _this = rootEl ? rootEl[expando] : window,
              sens = options.scrollSensitivity,
              speed = options.scrollSpeed,

              x = evt.clientX,
              y = evt.clientY,

              winWidth = window.innerWidth,
              winHeight = window.innerHeight,

              scrollThisInstance = false;

          // Detect scrollEl
          if (scrollParentEl !== rootEl) {
            _clearAutoScrolls();

            scrollEl = options.scroll;
            scrollCustomFn = options.scrollFn;

            if (scrollEl === true) {
              scrollEl = _getParentAutoScrollElement(rootEl, true);
              scrollParentEl = scrollEl;
            }
          }


          var layersOut = 0;
          var currentParent = scrollEl;
          do {
            var	el = currentParent,
                rect = _getRect(el),

                top = rect.top,
                bottom = rect.bottom,
                left = rect.left,
                right = rect.right,

                width = rect.width,
                height = rect.height,

                scrollWidth,
                scrollHeight,

                css,

                vx,
                vy,

                canScrollX,
                canScrollY,

                scrollPosX,
                scrollPosY;


            if (el !== win) {
              scrollWidth = el.scrollWidth;
              scrollHeight = el.scrollHeight;

              css = _css(el);

              canScrollX = width < scrollWidth && (css.overflowX === 'auto' || css.overflowX === 'scroll');
              canScrollY = height < scrollHeight && (css.overflowY === 'auto' || css.overflowY === 'scroll');

              scrollPosX = el.scrollLeft;
              scrollPosY = el.scrollTop;
            } else {
              scrollWidth = document.documentElement.scrollWidth;
              scrollHeight = document.documentElement.scrollHeight;

              css = _css(document.documentElement);

              canScrollX = width < scrollWidth && (css.overflowX === 'auto' || css.overflowX === 'scroll' || css.overflowX === 'visible');
              canScrollY = height < scrollHeight && (css.overflowY === 'auto' || css.overflowY === 'scroll' || css.overflowY === 'visible');

              scrollPosX = document.documentElement.scrollLeft;
              scrollPosY = document.documentElement.scrollTop;
            }

            vx = canScrollX && (abs(right - x) <= sens && (scrollPosX + width) < scrollWidth) - (abs(left - x) <= sens && !!scrollPosX);

            vy = canScrollY && (abs(bottom - y) <= sens && (scrollPosY + height) < scrollHeight) - (abs(top - y) <= sens && !!scrollPosY);


            if (!autoScrolls[layersOut]) {
              for (var i = 0; i <= layersOut; i++) {
                if (!autoScrolls[i]) {
                  autoScrolls[i] = {};
                }
              }
            }

            if (autoScrolls[layersOut].vx != vx || autoScrolls[layersOut].vy != vy || autoScrolls[layersOut].el !== el) {
              autoScrolls[layersOut].el = el;
              autoScrolls[layersOut].vx = vx;
              autoScrolls[layersOut].vy = vy;

              clearInterval(autoScrolls[layersOut].pid);

              if (el && (vx != 0 || vy != 0)) {
                scrollThisInstance = true;
                /* jshint loopfunc:true */
                autoScrolls[layersOut].pid = setInterval((function () {
                  // emulate drag over during autoscroll (fallback), emulating native DnD behaviour
                  if (isFallback && this.layer === 0) {
                    Sortable.active._emulateDragOver(true);
                  }
                  var scrollOffsetY = autoScrolls[this.layer].vy ? autoScrolls[this.layer].vy * speed : 0;
                  var scrollOffsetX = autoScrolls[this.layer].vx ? autoScrolls[this.layer].vx * speed : 0;

                  if ('function' === typeof(scrollCustomFn)) {
                    if (scrollCustomFn.call(_this, scrollOffsetX, scrollOffsetY, evt, touchEvt, autoScrolls[this.layer].el) !== 'continue') {
                      return;
                    }
                  }
                  if (autoScrolls[this.layer].el === win) {
                    win.scrollTo(win.pageXOffset + scrollOffsetX, win.pageYOffset + scrollOffsetY);
                  } else {
                    autoScrolls[this.layer].el.scrollTop += scrollOffsetY;
                    autoScrolls[this.layer].el.scrollLeft += scrollOffsetX;
                  }
                }).bind({layer: layersOut}), 24);
              }
            }
            layersOut++;
          } while (options.bubbleScroll && currentParent !== win && (currentParent = _getParentAutoScrollElement(currentParent, false)));
          scrolling = scrollThisInstance; // in case another function catches scrolling as false in between when it is not
        }
      }, 30),

      _clearAutoScrolls = function () {
        autoScrolls.forEach(function(autoScroll) {
          clearInterval(autoScroll.pid);
        });
        autoScrolls = [];
      },

      _prepareGroup = function (options) {
        function toFn(value, pull) {
          return function(to, from, dragEl, evt) {
            var sameGroup = to.options.group.name &&
                from.options.group.name &&
                to.options.group.name === from.options.group.name;

            if (value == null && (pull || sameGroup)) {
              // Default pull value
              // Default pull and put value if same group
              return true;
            } else if (value == null || value === false) {
              return false;
            } else if (pull && value === 'clone') {
              return value;
            } else if (typeof value === 'function') {
              return toFn(value(to, from, dragEl, evt), pull)(to, from, dragEl, evt);
            } else {
              var otherGroup = (pull ? to : from).options.group.name;

              return (value === true ||
                  (typeof value === 'string' && value === otherGroup) ||
                  (value.join && value.indexOf(otherGroup) > -1));
            }
          };
        }

        var group = {};
        var originalGroup = options.group;

        if (!originalGroup || typeof originalGroup != 'object') {
          originalGroup = {name: originalGroup};
        }

        group.name = originalGroup.name;
        group.checkPull = toFn(originalGroup.pull, true);
        group.checkPut = toFn(originalGroup.put);
        group.revertClone = originalGroup.revertClone;

        options.group = group;
      },

      _checkAlignment = function(evt) {
        if (!dragEl || !dragEl.parentNode) return;
        dragEl.parentNode[expando] && dragEl.parentNode[expando]._computeIsAligned(evt);
      },

      _isTrueParentSortable = function(el, target) {
        var trueParent = target;
        while (!trueParent[expando]) {
          trueParent = trueParent.parentNode;
        }

        return el === trueParent;
      },

      _artificalBubble = function(sortable, originalEvt, method) {
        // Artificial IE bubbling
        var nextParent = sortable.parentNode;
        while (nextParent && !nextParent[expando]) {
          nextParent = nextParent.parentNode;
        }

        if (nextParent) {
          nextParent[expando][method](_extend(originalEvt, {
            artificialBubble: true
          }));
        }
      },

      _hideGhostForTarget = function() {
        if (!supportCssPointerEvents && ghostEl) {
          _css(ghostEl, 'display', 'none');
        }
      },

      _unhideGhostForTarget = function() {
        if (!supportCssPointerEvents && ghostEl) {
          _css(ghostEl, 'display', '');
        }
      };


  // #1184 fix - Prevent click event on fallback if dragged but item not changed position
  document.addEventListener('click', function(evt) {
    if (ignoreNextClick) {
      evt.preventDefault();
      evt.stopPropagation && evt.stopPropagation();
      evt.stopImmediatePropagation && evt.stopImmediatePropagation();
      ignoreNextClick = false;
      return false;
    }
  }, true);

  var nearestEmptyInsertDetectEvent = function(evt) {
    evt = evt.touches ? evt.touches[0] : evt;
    if (dragEl) {
      var nearest = _detectNearestEmptySortable(evt.clientX, evt.clientY);

      if (nearest) {
        nearest[expando]._onDragOver({
          clientX: evt.clientX,
          clientY: evt.clientY,
          target: nearest,
          rootEl: nearest
        });
      }
    }
  };
  // We do not want this to be triggered if completed (bubbling canceled), so only define it here
  _on(document, 'dragover', nearestEmptyInsertDetectEvent);
  _on(document, 'mousemove', nearestEmptyInsertDetectEvent);
  _on(document, 'touchmove', nearestEmptyInsertDetectEvent);

  /**
   * @class  Sortable
   * @param  {HTMLElement}  el
   * @param  {Object}       [options]
   */
  function Sortable(el, options) {
    if (!(el && el.nodeType && el.nodeType === 1)) {
      throw 'Sortable: `el` must be HTMLElement, not ' + {}.toString.call(el);
    }

    this.el = el; // root element
    this.options = options = _extend({}, options);


    // Export instance
    el[expando] = this;

    // Default options
    var defaults = {
      group: null,
      sort: true,
      disabled: false,
      store: null,
      handle: null,
      scroll: true,
      scrollSensitivity: 30,
      scrollSpeed: 10,
      bubbleScroll: true,
      draggable: /[uo]l/i.test(el.nodeName) ? '>li' : '>*',
      swapThreshold: 1, // percentage; 0 <= x <= 1
      invertSwap: false, // invert always
      invertedSwapThreshold: null, // will be set to same as swapThreshold if default
      removeCloneOnHide: true,
      direction: function() {
        return _detectDirection(el, this.options);
      },
      ghostClass: 'sortable-ghost',
      chosenClass: 'sortable-chosen',
      dragClass: 'sortable-drag',
      ignore: 'a, img',
      filter: null,
      preventOnFilter: true,
      animation: 0,
      easing: null,
      setData: function (dataTransfer, dragEl) {
        dataTransfer.setData('Text', dragEl.textContent);
      },
      dropBubble: false,
      dragoverBubble: false,
      dataIdAttr: 'data-id',
      delay: 0,
      touchStartThreshold: parseInt(window.devicePixelRatio, 10) || 1,
      forceFallback: false,
      fallbackClass: 'sortable-fallback',
      fallbackOnBody: false,
      fallbackTolerance: 0,
      fallbackOffset: {x: 0, y: 0},
      supportPointer: Sortable.supportPointer !== false && (
          ('PointerEvent' in window) ||
          window.navigator && ('msPointerEnabled' in window.navigator) // microsoft
      ),
      emptyInsertThreshold: 5
    };


    // Set default options
    for (var name in defaults) {
      !(name in options) && (options[name] = defaults[name]);
    }

    _prepareGroup(options);

    // Bind all private methods
    for (var fn in this) {
      if (fn.charAt(0) === '_' && typeof this[fn] === 'function') {
        this[fn] = this[fn].bind(this);
      }
    }

    // Setup drag mode
    this.nativeDraggable = options.forceFallback ? false : supportDraggable;

    // Bind events
    if (options.supportPointer) {
      _on(el, 'pointerdown', this._onTapStart);
    } else {
      _on(el, 'mousedown', this._onTapStart);
      _on(el, 'touchstart', this._onTapStart);
    }

    if (this.nativeDraggable) {
      _on(el, 'dragover', this);
      _on(el, 'dragenter', this);
    }

    sortables.push(this.el);

    // Restore sorting
    options.store && options.store.get && this.sort(options.store.get(this) || []);
  }

  Sortable.prototype = /** @lends Sortable.prototype */ {
    constructor: Sortable,

    _computeIsAligned: function(evt) {
      var target;

      if (ghostEl && !supportCssPointerEvents) {
        _hideGhostForTarget();
        target = document.elementFromPoint(evt.clientX, evt.clientY);
        _unhideGhostForTarget();
      } else {
        target = evt.target;
      }

      target = _closest(target, this.options.draggable, this.el, false);
      if (_alignedSilent) return;
      if (!dragEl || dragEl.parentNode !== this.el) return;

      var children = this.el.children;
      for (var i = 0; i < children.length; i++) {
        // Don't change for target in case it is changed to aligned before onDragOver is fired
        if (_closest(children[i], this.options.draggable, this.el, false) && children[i] !== target) {
          children[i].sortableMouseAligned = _isClientInRowColumn(evt.clientX, evt.clientY, children[i], this._getDirection(evt, null), this.options);
        }
      }
      // Used for nulling last target when not in element, nothing to do with checking if aligned
      if (!_closest(target, this.options.draggable, this.el, true)) {
        lastTarget = null;
      }

      _alignedSilent = true;
      setTimeout(function() {
        _alignedSilent = false;
      }, 30);

    },

    _getDirection: function(evt, target) {
      return (typeof this.options.direction === 'function') ? this.options.direction.call(this, evt, target, dragEl) : this.options.direction;
    },

    _onTapStart: function (/** Event|TouchEvent */evt) {
      if (!evt.cancelable) return;
      var _this = this,
          el = this.el,
          options = this.options,
          preventOnFilter = options.preventOnFilter,
          type = evt.type,
          touch = evt.touches && evt.touches[0],
          target = (touch || evt).target,
          originalTarget = evt.target.shadowRoot && ((evt.path && evt.path[0]) || (evt.composedPath && evt.composedPath()[0])) || target,
          filter = options.filter,
          startIndex;

      _saveInputCheckedState(el);


      // IE: Calls events in capture mode if event element is nested. This ensures only correct element's _onTapStart goes through.
      // This process is also done in _onDragOver
      if (IE11OrLess && !evt.artificialBubble && !_isTrueParentSortable(el, target)) {
        return;
      }

      // Don't trigger start event when an element is been dragged, otherwise the evt.oldindex always wrong when set option.group.
      if (dragEl) {
        return;
      }

      if (/mousedown|pointerdown/.test(type) && evt.button !== 0 || options.disabled) {
        return; // only left button and enabled
      }

      // cancel dnd if original target is content editable
      if (originalTarget.isContentEditable) {
        return;
      }

      target = _closest(target, options.draggable, el, false);

      if (!target) {
        if (IE11OrLess) {
          _artificalBubble(el, evt, '_onTapStart');
        }
        return;
      }

      if (lastDownEl === target) {
        // Ignoring duplicate `down`
        return;
      }

      // Get the index of the dragged element within its parent
      startIndex = _index(target, options.draggable);

      // Check filter
      if (typeof filter === 'function') {
        if (filter.call(this, evt, target, this)) {
          _dispatchEvent(_this, originalTarget, 'filter', target, el, el, startIndex);
          preventOnFilter && evt.cancelable && evt.preventDefault();
          return; // cancel dnd
        }
      }
      else if (filter) {
        filter = filter.split(',').some(function (criteria) {
          criteria = _closest(originalTarget, criteria.trim(), el, false);

          if (criteria) {
            _dispatchEvent(_this, criteria, 'filter', target, el, el, startIndex);
            return true;
          }
        });

        if (filter) {
          preventOnFilter && evt.cancelable && evt.preventDefault();
          return; // cancel dnd
        }
      }

      if (options.handle && !_closest(originalTarget, options.handle, el, false)) {
        return;
      }

      // Prepare `dragstart`
      this._prepareDragStart(evt, touch, target, startIndex);
    },


    _handleAutoScroll: function(evt, fallback) {
      if (!dragEl || !this.options.scroll) return;
      var x = evt.clientX,
          y = evt.clientY,

          elem = document.elementFromPoint(x, y),
          _this = this;

      // IE does not seem to have native autoscroll,
      // Edge's autoscroll seems too conditional,
      // Firefox and Chrome are good
      if (fallback || Edge || IE11OrLess) {
        _autoScroll(evt, _this.options, elem, fallback);

        // Listener for pointer element change
        var ogElemScroller = _getParentAutoScrollElement(elem, true);
        if (
            scrolling &&
            (
                !pointerElemChangedInterval ||
                x !== lastPointerElemX ||
                y !== lastPointerElemY
            )
        ) {

          pointerElemChangedInterval && clearInterval(pointerElemChangedInterval);
          // Detect for pointer elem change, emulating native DnD behaviour
          pointerElemChangedInterval = setInterval(function() {
            if (!dragEl) return;
            // could also check if scroll direction on newElem changes due to parent autoscrolling
            var newElem = _getParentAutoScrollElement(document.elementFromPoint(x, y), true);
            if (newElem !== ogElemScroller) {
              ogElemScroller = newElem;
              _clearAutoScrolls();
              _autoScroll(evt, _this.options, ogElemScroller, fallback);
            }
          }, 10);
          lastPointerElemX = x;
          lastPointerElemY = y;
        }

      } else {
        // if DnD is enabled (and browser has good autoscrolling), first autoscroll will already scroll, so get parent autoscroll of first autoscroll
        if (!_this.options.bubbleScroll || _getParentAutoScrollElement(elem, true) === window) {
          _clearAutoScrolls();
          return;
        }
        _autoScroll(evt, _this.options, _getParentAutoScrollElement(elem, false), false);
      }
    },

    _prepareDragStart: function (/** Event */evt, /** Touch */touch, /** HTMLElement */target, /** Number */startIndex) {
      var _this = this,
          el = _this.el,
          options = _this.options,
          ownerDocument = el.ownerDocument,
          dragStartFn;

      if (target && !dragEl && (target.parentNode === el)) {
        rootEl = el;
        dragEl = target;
        parentEl = dragEl.parentNode;
        nextEl = dragEl.nextSibling;
        lastDownEl = target;
        activeGroup = options.group;
        oldIndex = startIndex;

        tapEvt = {
          target: dragEl,
          clientX: (touch || evt).clientX,
          clientY: (touch || evt).clientY
        };

        this._lastX = (touch || evt).clientX;
        this._lastY = (touch || evt).clientY;

        dragEl.style['will-change'] = 'all';
        // undo animation if needed
        dragEl.style.transition = '';
        dragEl.style.transform = '';

        dragStartFn = function () {
          // Delayed drag has been triggered
          // we can re-enable the events: touchmove/mousemove
          _this._disableDelayedDrag();

          // Make the element draggable
          dragEl.draggable = _this.nativeDraggable;

          // Bind the events: dragstart/dragend
          _this._triggerDragStart(evt, touch);

          // Drag start event
          _dispatchEvent(_this, rootEl, 'choose', dragEl, rootEl, rootEl, oldIndex);

          // Chosen item
          _toggleClass(dragEl, options.chosenClass, true);
        };

        // Disable "draggable"
        options.ignore.split(',').forEach(function (criteria) {
          _find(dragEl, criteria.trim(), _disableDraggable);
        });

        if (options.supportPointer) {
          _on(ownerDocument, 'pointerup', _this._onDrop);
        } else {
          _on(ownerDocument, 'mouseup', _this._onDrop);
          _on(ownerDocument, 'touchend', _this._onDrop);
          _on(ownerDocument, 'touchcancel', _this._onDrop);
        }

        if (options.delay) {
          // If the user moves the pointer or let go the click or touch
          // before the delay has been reached:
          // disable the delayed drag
          _on(ownerDocument, 'mouseup', _this._disableDelayedDrag);
          _on(ownerDocument, 'touchend', _this._disableDelayedDrag);
          _on(ownerDocument, 'touchcancel', _this._disableDelayedDrag);
          _on(ownerDocument, 'mousemove', _this._delayedDragTouchMoveHandler);
          _on(ownerDocument, 'touchmove', _this._delayedDragTouchMoveHandler);
          options.supportPointer && _on(ownerDocument, 'pointermove', _this._delayedDragTouchMoveHandler);

          _this._dragStartTimer = setTimeout(dragStartFn, options.delay);
        } else {
          dragStartFn();
        }
      }
    },

    _delayedDragTouchMoveHandler: function (/** TouchEvent|PointerEvent **/e) {
      var touch = e.touches ? e.touches[0] : e;
      if (min(abs(touch.clientX - this._lastX), abs(touch.clientY - this._lastY))
          >= this.options.touchStartThreshold
      ) {
        this._disableDelayedDrag();
      }
    },

    _disableDelayedDrag: function () {
      var ownerDocument = this.el.ownerDocument;

      clearTimeout(this._dragStartTimer);
      _off(ownerDocument, 'mouseup', this._disableDelayedDrag);
      _off(ownerDocument, 'touchend', this._disableDelayedDrag);
      _off(ownerDocument, 'touchcancel', this._disableDelayedDrag);
      _off(ownerDocument, 'mousemove', this._delayedDragTouchMoveHandler);
      _off(ownerDocument, 'touchmove', this._delayedDragTouchMoveHandler);
      _off(ownerDocument, 'pointermove', this._delayedDragTouchMoveHandler);
    },

    _triggerDragStart: function (/** Event */evt, /** Touch */touch) {
      touch = touch || (evt.pointerType == 'touch' ? evt : null);

      if (!this.nativeDraggable || touch) {
        if (this.options.supportPointer) {
          _on(document, 'pointermove', this._onTouchMove);
        } else if (touch) {
          _on(document, 'touchmove', this._onTouchMove);
        } else {
          _on(document, 'mousemove', this._onTouchMove);
        }
      } else {
        _on(dragEl, 'dragend', this);
        _on(rootEl, 'dragstart', this._onDragStart);
      }

      try {
        if (document.selection) {
          // Timeout neccessary for IE9
          _nextTick(function () {
            document.selection.empty();
          });
        } else {
          window.getSelection().removeAllRanges();
        }
      } catch (err) {
      }
    },

    _dragStarted: function (fallback) {
      awaitingDragStarted = false;
      if (rootEl && dragEl) {
        if (this.nativeDraggable) {
          _on(document, 'dragover', this._handleAutoScroll);
          _on(document, 'dragover', _checkAlignment);
        }
        var options = this.options;

        // Apply effect
        !fallback && _toggleClass(dragEl, options.dragClass, false);
        _toggleClass(dragEl, options.ghostClass, true);

        // In case dragging an animated element
        _css(dragEl, 'transform', '');

        Sortable.active = this;

        fallback && this._appendGhost();

        // Drag start event
        _dispatchEvent(this, rootEl, 'start', dragEl, rootEl, rootEl, oldIndex);
      } else {
        this._nulling();
      }
    },

    _emulateDragOver: function (bypassLastTouchCheck) {
      if (touchEvt) {
        if (this._lastX === touchEvt.clientX && this._lastY === touchEvt.clientY && !bypassLastTouchCheck) {
          return;
        }
        this._lastX = touchEvt.clientX;
        this._lastY = touchEvt.clientY;

        _hideGhostForTarget();

        var target = document.elementFromPoint(touchEvt.clientX, touchEvt.clientY);
        var parent = target;

        while (target && target.shadowRoot) {
          target = target.shadowRoot.elementFromPoint(touchEvt.clientX, touchEvt.clientY);
          parent = target;
        }

        if (parent) {
          do {
            if (parent[expando]) {
              var inserted;

              inserted = parent[expando]._onDragOver({
                clientX: touchEvt.clientX,
                clientY: touchEvt.clientY,
                target: target,
                rootEl: parent
              });

              if (inserted && !this.options.dragoverBubble) {
                break;
              }
            }

            target = parent; // store last element
          }
              /* jshint boss:true */
          while (parent = parent.parentNode);
        }
        dragEl.parentNode[expando]._computeIsAligned(touchEvt);

        _unhideGhostForTarget();
      }
    },


    _onTouchMove: function (/**TouchEvent*/evt) {
      if (tapEvt) {
        var	options = this.options,
            fallbackTolerance = options.fallbackTolerance,
            fallbackOffset = options.fallbackOffset,
            touch = evt.touches ? evt.touches[0] : evt,
            matrix = ghostEl && _matrix(ghostEl),
            scaleX = ghostEl && matrix && matrix.a,
            scaleY = ghostEl && matrix && matrix.d,
            dx = ((touch.clientX - tapEvt.clientX) + fallbackOffset.x) / (scaleX ? scaleX : 1),
            dy = ((touch.clientY - tapEvt.clientY) + fallbackOffset.y) / (scaleY ? scaleY : 1),
            translate3d = evt.touches ? 'translate3d(' + dx + 'px,' + dy + 'px,0)' : 'translate(' + dx + 'px,' + dy + 'px)';


        // only set the status to dragging, when we are actually dragging
        if (!Sortable.active && !awaitingDragStarted) {
          if (fallbackTolerance &&
              min(abs(touch.clientX - this._lastX), abs(touch.clientY - this._lastY)) < fallbackTolerance
          ) {
            return;
          }
          this._onDragStart(evt, true);
        }

        this._handleAutoScroll(touch, true);


        moved = true;
        touchEvt = touch;


        _css(ghostEl, 'webkitTransform', translate3d);
        _css(ghostEl, 'mozTransform', translate3d);
        _css(ghostEl, 'msTransform', translate3d);
        _css(ghostEl, 'transform', translate3d);

        evt.cancelable && evt.preventDefault();
      }
    },

    _appendGhost: function () {
      if (!ghostEl) {
        var rect = _getRect(dragEl, this.options.fallbackOnBody ? document.body : rootEl, true),
            css = _css(dragEl),
            options = this.options;

        ghostEl = dragEl.cloneNode(true);

        _toggleClass(ghostEl, options.ghostClass, false);
        _toggleClass(ghostEl, options.fallbackClass, true);
        _toggleClass(ghostEl, options.dragClass, true);

        _css(ghostEl, 'box-sizing', 'border-box');
        _css(ghostEl, 'margin', 0);
        _css(ghostEl, 'top', rect.top);
        _css(ghostEl, 'left', rect.left);
        _css(ghostEl, 'width', rect.width);
        _css(ghostEl, 'height', rect.height);
        _css(ghostEl, 'opacity', '0.8');
        _css(ghostEl, 'position', 'fixed');
        _css(ghostEl, 'zIndex', '100000');
        _css(ghostEl, 'pointerEvents', 'none');

        options.fallbackOnBody && document.body.appendChild(ghostEl) || rootEl.appendChild(ghostEl);
      }
    },

    _onDragStart: function (/**Event*/evt, /**boolean*/fallback) {
      var _this = this;
      var dataTransfer = evt.dataTransfer;
      var options = _this.options;

      // Setup clone
      cloneEl = _clone(dragEl);

      cloneEl.draggable = false;
      cloneEl.style['will-change'] = '';

      this._hideClone();

      _toggleClass(cloneEl, _this.options.chosenClass, false);


      // #1143: IFrame support workaround
      _this._cloneId = _nextTick(function () {
        if (!_this.options.removeCloneOnHide) {
          rootEl.insertBefore(cloneEl, dragEl);
        }
        _dispatchEvent(_this, rootEl, 'clone', dragEl);
      });


      !fallback && _toggleClass(dragEl, options.dragClass, true);

      // Set proper drop events
      if (fallback) {
        ignoreNextClick = true;
        _this._loopId = setInterval(_this._emulateDragOver, 50);
      } else {
        // Undo what was set in _prepareDragStart before drag started
        _off(document, 'mouseup', _this._onDrop);
        _off(document, 'touchend', _this._onDrop);
        _off(document, 'touchcancel', _this._onDrop);

        if (dataTransfer) {
          dataTransfer.effectAllowed = 'move';
          options.setData && options.setData.call(_this, dataTransfer, dragEl);
        }

        _on(document, 'drop', _this);

        // #1276 fix:
        _css(dragEl, 'transform', 'translateZ(0)');
      }

      awaitingDragStarted = true;

      _this._dragStartId = _nextTick(_this._dragStarted.bind(_this, fallback));
      _on(document, 'selectstart', _this);
    },

    // Returns true - if no further action is needed (either inserted or another condition)
    _onDragOver: function (/**Event*/evt) {
      var el = this.el,
          target = evt.target,
          dragRect,
          targetRect,
          revert,
          options = this.options,
          group = options.group,
          activeSortable = Sortable.active,
          isOwner = (activeGroup === group),
          canSort = options.sort,
          _this = this;

      if (_silent) return;

      // IE event order fix
      if (IE11OrLess && !evt.rootEl && !evt.artificialBubble && !_isTrueParentSortable(el, target)) {
        return;
      }

      // Return invocation when no further action is needed in another sortable
      function completed() {
        if (activeSortable) {
          // Set ghost class to new sortable's ghost class
          _toggleClass(dragEl, putSortable ? putSortable.options.ghostClass : activeSortable.options.ghostClass, false);
          _toggleClass(dragEl, options.ghostClass, true);
        }

        if (putSortable !== _this && _this !== Sortable.active) {
          putSortable = _this;
        } else if (_this === Sortable.active) {
          putSortable = null;
        }


        // Null lastTarget if it is not inside a previously swapped element
        if ((target === dragEl && !dragEl.animated) || (target === el && !target.animated)) {
          lastTarget = null;
        }
        // no bubbling and not fallback
        if (!options.dragoverBubble && !evt.rootEl && target !== document) {
          _this._handleAutoScroll(evt);
          dragEl.parentNode[expando]._computeIsAligned(evt);
        }

        !options.dragoverBubble && evt.stopPropagation && evt.stopPropagation();

        return true;
      }

      // Call when dragEl has been inserted
      function changed() {
        _dispatchEvent(_this, rootEl, 'change', target, el, rootEl, oldIndex, _index(dragEl, options.draggable), evt);
      }


      if (evt.preventDefault !== void 0) {
        evt.cancelable && evt.preventDefault();
      }


      moved = true;

      target = _closest(target, options.draggable, el, true);

      // target is dragEl or target is animated
      if (!!_closest(evt.target, null, dragEl, true) || target.animated) {
        return completed();
      }

      if (target !== dragEl) {
        ignoreNextClick = false;
      }

      if (activeSortable && !options.disabled &&
          (isOwner
                  ? canSort || (revert = !rootEl.contains(dragEl)) // Reverting item into the original list
                  : (
                      putSortable === this ||
                      (
                          (this.lastPutMode = activeGroup.checkPull(this, activeSortable, dragEl, evt)) &&
                          group.checkPut(this, activeSortable, dragEl, evt)
                      )
                  )
          )
      ) {
        var axis = this._getDirection(evt, target);

        dragRect = _getRect(dragEl);

        if (revert) {
          this._hideClone();
          parentEl = rootEl; // actualization

          if (nextEl) {
            rootEl.insertBefore(dragEl, nextEl);
          } else {
            rootEl.appendChild(dragEl);
          }

          return completed();
        }

        if ((el.children.length === 0) || (el.children[0] === ghostEl) ||
            _ghostIsLast(evt, axis, el) && !dragEl.animated
        ) {
          //assign target only if condition is true
          if (el.children.length !== 0 && el.children[0] !== ghostEl && el === evt.target) {
            target = _lastChild(el);
          }

          if (target) {
            targetRect = _getRect(target);
          }

          if (isOwner) {
            activeSortable._hideClone();
          } else {
            activeSortable._showClone(this);
          }

          if (_onMove(rootEl, el, dragEl, dragRect, target, targetRect, evt, !!target) !== false) {
            el.appendChild(dragEl);
            parentEl = el; // actualization
            realDragElRect = null;

            changed();
            this._animate(dragRect, dragEl);
            target && this._animate(targetRect, target);
            return completed();
          }
        }
        else if (target && target !== dragEl && target.parentNode === el) {
          var direction = 0,
              targetBeforeFirstSwap,
              aligned = target.sortableMouseAligned,
              differentLevel = dragEl.parentNode !== el,
              scrolledPastTop = _isScrolledPast(target, axis === 'vertical' ? 'top' : 'left');

          if (lastTarget !== target) {
            lastMode = null;
            targetBeforeFirstSwap = _getRect(target)[axis === 'vertical' ? 'top' : 'left'];
            pastFirstInvertThresh = false;
          }

          // Reference: https://www.lucidchart.com/documents/view/10fa0e93-e362-4126-aca2-b709ee56bd8b/0
          if (
              _isElInRowColumn(dragEl, target, axis) && aligned ||
              differentLevel ||
              scrolledPastTop ||
              options.invertSwap ||
              lastMode === 'insert' ||
              // Needed, in the case that we are inside target and inserted because not aligned... aligned will stay false while inside
              // and lastMode will change to 'insert', but we must swap
              lastMode === 'swap'
          ) {
            // New target that we will be inside
            if (lastMode !== 'swap') {
              isCircumstantialInvert = options.invertSwap || differentLevel || scrolling || scrolledPastTop;
            }

            direction = _getSwapDirection(evt, target, axis,
                options.swapThreshold, options.invertedSwapThreshold == null ? options.swapThreshold : options.invertedSwapThreshold,
                isCircumstantialInvert,
                lastTarget === target);
            lastMode = 'swap';
          } else {
            // Insert at position
            direction = _getInsertDirection(target, options);
            lastMode = 'insert';
          }
          if (direction === 0) return completed();

          realDragElRect = null;
          lastTarget = target;

          lastDirection = direction;

          targetRect = _getRect(target);

          var nextSibling = target.nextElementSibling,
              after = false;

          after = direction === 1;

          var moveVector = _onMove(rootEl, el, dragEl, dragRect, target, targetRect, evt, after);

          if (moveVector !== false) {
            if (moveVector === 1 || moveVector === -1) {
              after = (moveVector === 1);
            }

            _silent = true;
            setTimeout(_unsilent, 30);

            if (isOwner) {
              activeSortable._hideClone();
            } else {
              activeSortable._showClone(this);
            }

            if (after && !nextSibling) {
              el.appendChild(dragEl);
            } else {
              target.parentNode.insertBefore(dragEl, after ? nextSibling : target);
            }

            parentEl = dragEl.parentNode; // actualization

            // must be done before animation
            if (targetBeforeFirstSwap !== undefined && !isCircumstantialInvert) {
              targetMoveDistance = abs(targetBeforeFirstSwap - _getRect(target)[axis === 'vertical' ? 'top' : 'left']);
            }
            changed();
            !differentLevel && this._animate(targetRect, target);
            this._animate(dragRect, dragEl);

            return completed();
          }
        }

        if (el.contains(dragEl)) {
          return completed();
        }
      }

      if (IE11OrLess && !evt.rootEl) {
        _artificalBubble(el, evt, '_onDragOver');
      }

      return false;
    },

    _animate: function (prevRect, target) {
      var ms = this.options.animation;

      if (ms) {
        var currentRect = _getRect(target);

        if (target === dragEl) {
          realDragElRect = currentRect;
        }

        if (prevRect.nodeType === 1) {
          prevRect = _getRect(prevRect);
        }

        // Check if actually moving position
        if ((prevRect.left + prevRect.width / 2) !== (currentRect.left + currentRect.width / 2)
            || (prevRect.top + prevRect.height / 2) !== (currentRect.top + currentRect.height / 2)
        ) {
          var matrix = _matrix(this.el),
              scaleX = matrix && matrix.a,
              scaleY = matrix && matrix.d;

          _css(target, 'transition', 'none');
          _css(target, 'transform', 'translate3d('
              + (prevRect.left - currentRect.left) / (scaleX ? scaleX : 1) + 'px,'
              + (prevRect.top - currentRect.top) / (scaleY ? scaleY : 1) + 'px,0)'
          );

          forRepaintDummy = target.offsetWidth; // repaint
          _css(target, 'transition', 'transform ' + ms + 'ms' + (this.options.easing ? ' ' + this.options.easing : ''));
          _css(target, 'transform', 'translate3d(0,0,0)');
        }

        (typeof target.animated === 'number') && clearTimeout(target.animated);
        target.animated = setTimeout(function () {
          _css(target, 'transition', '');
          _css(target, 'transform', '');
          target.animated = false;
        }, ms);
      }
    },

    _offUpEvents: function () {
      var ownerDocument = this.el.ownerDocument;

      _off(document, 'touchmove', this._onTouchMove);
      _off(document, 'pointermove', this._onTouchMove);
      _off(ownerDocument, 'mouseup', this._onDrop);
      _off(ownerDocument, 'touchend', this._onDrop);
      _off(ownerDocument, 'pointerup', this._onDrop);
      _off(ownerDocument, 'touchcancel', this._onDrop);
      _off(document, 'selectstart', this);
    },

    _onDrop: function (/**Event*/evt) {
      var el = this.el,
          options = this.options;
      awaitingDragStarted = false;
      scrolling = false;
      isCircumstantialInvert = false;
      pastFirstInvertThresh = false;

      clearInterval(this._loopId);

      clearInterval(pointerElemChangedInterval);
      _clearAutoScrolls();
      _cancelThrottle();

      clearTimeout(this._dragStartTimer);

      _cancelNextTick(this._cloneId);
      _cancelNextTick(this._dragStartId);

      // Unbind events
      _off(document, 'mousemove', this._onTouchMove);


      if (this.nativeDraggable) {
        _off(document, 'drop', this);
        _off(el, 'dragstart', this._onDragStart);
        _off(document, 'dragover', this._handleAutoScroll);
        _off(document, 'dragover', _checkAlignment);
      }

      this._offUpEvents();

      if (evt) {
        if (moved) {
          evt.cancelable && evt.preventDefault();
          !options.dropBubble && evt.stopPropagation();
        }

        ghostEl && ghostEl.parentNode && ghostEl.parentNode.removeChild(ghostEl);

        if (rootEl === parentEl || (putSortable && putSortable.lastPutMode !== 'clone')) {
          // Remove clone
          cloneEl && cloneEl.parentNode && cloneEl.parentNode.removeChild(cloneEl);
        }

        if (dragEl) {
          if (this.nativeDraggable) {
            _off(dragEl, 'dragend', this);
          }

          _disableDraggable(dragEl);
          dragEl.style['will-change'] = '';

          // Remove class's
          _toggleClass(dragEl, putSortable ? putSortable.options.ghostClass : this.options.ghostClass, false);
          _toggleClass(dragEl, this.options.chosenClass, false);

          // Drag stop event
          _dispatchEvent(this, rootEl, 'unchoose', dragEl, parentEl, rootEl, oldIndex, null, evt);

          if (rootEl !== parentEl) {
            newIndex = _index(dragEl, options.draggable);

            if (newIndex >= 0) {
              // Add event
              _dispatchEvent(null, parentEl, 'add', dragEl, parentEl, rootEl, oldIndex, newIndex, evt);

              // Remove event
              _dispatchEvent(this, rootEl, 'remove', dragEl, parentEl, rootEl, oldIndex, newIndex, evt);

              // drag from one list and drop into another
              _dispatchEvent(null, parentEl, 'sort', dragEl, parentEl, rootEl, oldIndex, newIndex, evt);
              _dispatchEvent(this, rootEl, 'sort', dragEl, parentEl, rootEl, oldIndex, newIndex, evt);
            }

            putSortable && putSortable.save();
          }
          else {
            if (dragEl.nextSibling !== nextEl) {
              // Get the index of the dragged element within its parent
              newIndex = _index(dragEl, options.draggable);

              if (newIndex >= 0) {
                // drag & drop within the same list
                _dispatchEvent(this, rootEl, 'update', dragEl, parentEl, rootEl, oldIndex, newIndex, evt);
                _dispatchEvent(this, rootEl, 'sort', dragEl, parentEl, rootEl, oldIndex, newIndex, evt);
              }
            }
          }

          if (Sortable.active) {
            /* jshint eqnull:true */
            if (newIndex == null || newIndex === -1) {
              newIndex = oldIndex;
            }

            _dispatchEvent(this, rootEl, 'end', dragEl, parentEl, rootEl, oldIndex, newIndex, evt);

            // Save sorting
            this.save();
          }
        }

      }
      this._nulling();
    },

    _nulling: function() {
      rootEl =
          dragEl =
              parentEl =
                  ghostEl =
                      nextEl =
                          cloneEl =
                              lastDownEl =

                                  scrollEl =
                                      scrollParentEl =
                                          autoScrolls.length =

                                              pointerElemChangedInterval =
                                                  lastPointerElemX =
                                                      lastPointerElemY =

                                                          tapEvt =
                                                              touchEvt =

                                                                  moved =
                                                                      newIndex =
                                                                          oldIndex =

                                                                              lastTarget =
                                                                                  lastDirection =

                                                                                      forRepaintDummy =
                                                                                          realDragElRect =

                                                                                              putSortable =
                                                                                                  activeGroup =
                                                                                                      Sortable.active = null;

      savedInputChecked.forEach(function (el) {
        el.checked = true;
      });

      savedInputChecked.length = 0;
    },

    handleEvent: function (/**Event*/evt) {
      switch (evt.type) {
        case 'drop':
        case 'dragend':
          this._onDrop(evt);
          break;

        case 'dragenter':
        case 'dragover':
          if (dragEl) {
            this._onDragOver(evt);
            _globalDragOver(evt);
          }
          break;

        case 'selectstart':
          evt.preventDefault();
          break;
      }
    },


    /**
     * Serializes the item into an array of string.
     * @returns {String[]}
     */
    toArray: function () {
      var order = [],
          el,
          children = this.el.children,
          i = 0,
          n = children.length,
          options = this.options;

      for (; i < n; i++) {
        el = children[i];
        if (_closest(el, options.draggable, this.el, false)) {
          order.push(el.getAttribute(options.dataIdAttr) || _generateId(el));
        }
      }

      return order;
    },


    /**
     * Sorts the elements according to the array.
     * @param  {String[]}  order  order of the items
     */
    sort: function (order) {
      var items = {}, rootEl = this.el;

      this.toArray().forEach(function (id, i) {
        var el = rootEl.children[i];

        if (_closest(el, this.options.draggable, rootEl, false)) {
          items[id] = el;
        }
      }, this);

      order.forEach(function (id) {
        if (items[id]) {
          rootEl.removeChild(items[id]);
          rootEl.appendChild(items[id]);
        }
      });
    },


    /**
     * Save the current sorting
     */
    save: function () {
      var store = this.options.store;
      store && store.set && store.set(this);
    },


    /**
     * For each element in the set, get the first element that matches the selector by testing the element itself and traversing up through its ancestors in the DOM tree.
     * @param   {HTMLElement}  el
     * @param   {String}       [selector]  default: `options.draggable`
     * @returns {HTMLElement|null}
     */
    closest: function (el, selector) {
      return _closest(el, selector || this.options.draggable, this.el, false);
    },


    /**
     * Set/get option
     * @param   {string} name
     * @param   {*}      [value]
     * @returns {*}
     */
    option: function (name, value) {
      var options = this.options;

      if (value === void 0) {
        return options[name];
      } else {
        options[name] = value;

        if (name === 'group') {
          _prepareGroup(options);
        }
      }
    },


    /**
     * Destroy
     */
    destroy: function () {
      var el = this.el;

      el[expando] = null;

      _off(el, 'mousedown', this._onTapStart);
      _off(el, 'touchstart', this._onTapStart);
      _off(el, 'pointerdown', this._onTapStart);

      if (this.nativeDraggable) {
        _off(el, 'dragover', this);
        _off(el, 'dragenter', this);
      }
      // Remove draggable attributes
      Array.prototype.forEach.call(el.querySelectorAll('[draggable]'), function (el) {
        el.removeAttribute('draggable');
      });

      this._onDrop();

      sortables.splice(sortables.indexOf(this.el), 1);

      this.el = el = null;
    },

    _hideClone: function() {
      if (!cloneEl.cloneHidden) {
        _css(cloneEl, 'display', 'none');
        cloneEl.cloneHidden = true;
        if (cloneEl.parentNode && this.options.removeCloneOnHide) {
          cloneEl.parentNode.removeChild(cloneEl);
        }
      }
    },

    _showClone: function(putSortable) {
      if (putSortable.lastPutMode !== 'clone') {
        this._hideClone();
        return;
      }

      if (cloneEl.cloneHidden) {
        // show clone at dragEl or original position
        if (rootEl.contains(dragEl) && !this.options.group.revertClone) {
          rootEl.insertBefore(cloneEl, dragEl);
        } else if (nextEl) {
          rootEl.insertBefore(cloneEl, nextEl);
        } else {
          rootEl.appendChild(cloneEl);
        }

        if (this.options.group.revertClone) {
          this._animate(dragEl, cloneEl);
        }
        _css(cloneEl, 'display', '');
        cloneEl.cloneHidden = false;
      }
    }
  };

  function _closest(/**HTMLElement*/el, /**String*/selector, /**HTMLElement*/ctx, includeCTX) {
    if (el) {
      ctx = ctx || document;

      do {
        if (
            selector != null &&
            (
                selector[0] === '>' && el.parentNode === ctx && _matches(el, selector.substring(1)) ||
                _matches(el, selector)
            ) ||
            includeCTX && el === ctx
        ) {
          return el;
        }

        if (el === ctx) break;
        /* jshint boss:true */
      } while (el = _getParentOrHost(el));
    }

    return null;
  }


  function _getParentOrHost(el) {
    return (el.host && el !== document && el.host.nodeType)
        ? el.host
        : el.parentNode;
  }


  function _globalDragOver(/**Event*/evt) {
    if (evt.dataTransfer) {
      evt.dataTransfer.dropEffect = 'move';
    }
    evt.cancelable && evt.preventDefault();
  }


  function _on(el, event, fn) {
    el.addEventListener(event, fn, captureMode);
  }


  function _off(el, event, fn) {
    el.removeEventListener(event, fn, captureMode);
  }


  function _toggleClass(el, name, state) {
    if (el && name) {
      if (el.classList) {
        el.classList[state ? 'add' : 'remove'](name);
      }
      else {
        var className = (' ' + el.className + ' ').replace(R_SPACE, ' ').replace(' ' + name + ' ', ' ');
        el.className = (className + (state ? ' ' + name : '')).replace(R_SPACE, ' ');
      }
    }
  }


  function _css(el, prop, val) {
    var style = el && el.style;

    if (style) {
      if (val === void 0) {
        if (document.defaultView && document.defaultView.getComputedStyle) {
          val = document.defaultView.getComputedStyle(el, '');
        }
        else if (el.currentStyle) {
          val = el.currentStyle;
        }

        return prop === void 0 ? val : val[prop];
      }
      else {
        if (!(prop in style) && prop.indexOf('webkit') === -1) {
          prop = '-webkit-' + prop;
        }

        style[prop] = val + (typeof val === 'string' ? '' : 'px');
      }
    }
  }

  function _matrix(el) {
    var appliedTransforms = '';
    do {
      var transform = _css(el, 'transform');

      if (transform && transform !== 'none') {
        appliedTransforms = transform + ' ' + appliedTransforms;
      }
      /* jshint boss:true */
    } while (el = el.parentNode);

    if (window.DOMMatrix) {
      return new DOMMatrix(appliedTransforms);
    } else if (window.WebKitCSSMatrix) {
      return new WebKitCSSMatrix(appliedTransforms);
    } else if (window.CSSMatrix) {
      return new CSSMatrix(appliedTransforms);
    }
  }


  function _find(ctx, tagName, iterator) {
    if (ctx) {
      var list = ctx.getElementsByTagName(tagName), i = 0, n = list.length;

      if (iterator) {
        for (; i < n; i++) {
          iterator(list[i], i);
        }
      }

      return list;
    }

    return [];
  }



  function _dispatchEvent(sortable, rootEl, name, targetEl, toEl, fromEl, startIndex, newIndex, originalEvt) {
    sortable = (sortable || rootEl[expando]);
    var evt,
        options = sortable.options,
        onName = 'on' + name.charAt(0).toUpperCase() + name.substr(1);
    // Support for new CustomEvent feature
    if (window.CustomEvent && !IE11OrLess && !Edge) {
      evt = new CustomEvent(name, {
        bubbles: true,
        cancelable: true
      });
    } else {
      evt = document.createEvent('Event');
      evt.initEvent(name, true, true);
    }

    evt.to = toEl || rootEl;
    evt.from = fromEl || rootEl;
    evt.item = targetEl || rootEl;
    evt.clone = cloneEl;

    evt.oldIndex = startIndex;
    evt.newIndex = newIndex;

    evt.originalEvent = originalEvt;

    if (rootEl) {
      rootEl.dispatchEvent(evt);
    }

    if (options[onName]) {
      options[onName].call(sortable, evt);
    }
  }


  function _onMove(fromEl, toEl, dragEl, dragRect, targetEl, targetRect, originalEvt, willInsertAfter) {
    var evt,
        sortable = fromEl[expando],
        onMoveFn = sortable.options.onMove,
        retVal;
    // Support for new CustomEvent feature
    if (window.CustomEvent && !IE11OrLess && !Edge) {
      evt = new CustomEvent('move', {
        bubbles: true,
        cancelable: true
      });
    } else {
      evt = document.createEvent('Event');
      evt.initEvent('move', true, true);
    }

    evt.to = toEl;
    evt.from = fromEl;
    evt.dragged = dragEl;
    evt.draggedRect = dragRect;
    evt.related = targetEl || toEl;
    evt.relatedRect = targetRect || _getRect(toEl);
    evt.willInsertAfter = willInsertAfter;

    evt.originalEvent = originalEvt;

    fromEl.dispatchEvent(evt);

    if (onMoveFn) {
      retVal = onMoveFn.call(sortable, evt, originalEvt);
    }

    return retVal;
  }

  function _disableDraggable(el) {
    el.draggable = false;
  }

  function _unsilent() {
    _silent = false;
  }

  /**
   * Gets nth child of el, ignoring hidden children, sortable's elements (does not ignore clone if it's visible)
   * and non-draggable elements
   * @param  {HTMLElement} el       The parent element
   * @param  {Number} childNum      The index of the child
   * @param  {Object} options       Parent Sortable's options
   * @return {HTMLElement}          The child at index childNum, or null if not found
   */
  function _getChild(el, childNum, options) {
    var currentChild = 0,
        i = 0,
        children = el.children;

    while (i < children.length) {
      if (
          children[i].style.display !== 'none' &&
          children[i] !== ghostEl &&
          children[i] !== dragEl &&
          _closest(children[i], options.draggable, el, false)
      ) {
        if (currentChild === childNum) {
          return children[i];
        }
        currentChild++;
      }

      i++;
    }
    return null;
  }

  /**
   * Gets the last child in the el, ignoring ghostEl or invisible elements (clones)
   * @param  {HTMLElement} el       Parent element
   * @return {HTMLElement}          The last child, ignoring ghostEl
   */
  function _lastChild(el) {
    var last = el.lastElementChild;

    while (last === ghostEl || last.style.display === 'none') {
      last = last.previousElementSibling;

      if (!last) break;
    }

    return last || null;
  }

  function _ghostIsLast(evt, axis, el) {
    var elRect = _getRect(_lastChild(el)),
        mouseOnAxis = axis === 'vertical' ? evt.clientY : evt.clientX,
        mouseOnOppAxis = axis === 'vertical' ? evt.clientX : evt.clientY,
        targetS2 = axis === 'vertical' ? elRect.bottom : elRect.right,
        targetS1Opp = axis === 'vertical' ? elRect.left : elRect.top,
        targetS2Opp = axis === 'vertical' ? elRect.right : elRect.bottom,
        spacer = 10;

    return (
        axis === 'vertical' ?
            (mouseOnOppAxis > targetS2Opp + spacer || mouseOnOppAxis <= targetS2Opp && mouseOnAxis > targetS2 && mouseOnOppAxis >= targetS1Opp) :
            (mouseOnAxis > targetS2 && mouseOnOppAxis > targetS1Opp || mouseOnAxis <= targetS2 && mouseOnOppAxis > targetS2Opp + spacer)
    );
  }

  function _getSwapDirection(evt, target, axis, swapThreshold, invertedSwapThreshold, invertSwap, isLastTarget) {
    var targetRect = _getRect(target),
        mouseOnAxis = axis === 'vertical' ? evt.clientY : evt.clientX,
        targetLength = axis === 'vertical' ? targetRect.height : targetRect.width,
        targetS1 = axis === 'vertical' ? targetRect.top : targetRect.left,
        targetS2 = axis === 'vertical' ? targetRect.bottom : targetRect.right,
        dragRect = _getRect(dragEl),
        invert = false;


    if (!invertSwap) {
      // Never invert or create dragEl shadow when target movemenet causes mouse to move past the end of regular swapThreshold
      if (isLastTarget && targetMoveDistance < targetLength * swapThreshold) { // multiplied only by swapThreshold because mouse will already be inside target by (1 - threshold) * targetLength / 2
        // check if past first invert threshold on side opposite of lastDirection
        if (!pastFirstInvertThresh &&
            (lastDirection === 1 ?
                    (
                        mouseOnAxis > targetS1 + targetLength * invertedSwapThreshold / 2
                    ) :
                    (
                        mouseOnAxis < targetS2 - targetLength * invertedSwapThreshold / 2
                    )
            )
        )
        {
          // past first invert threshold, do not restrict inverted threshold to dragEl shadow
          pastFirstInvertThresh = true;
        }

        if (!pastFirstInvertThresh) {
          var dragS1 = axis === 'vertical' ? dragRect.top : dragRect.left,
              dragS2 = axis === 'vertical' ? dragRect.bottom : dragRect.right;
          // dragEl shadow (target move distance shadow)
          if (
              lastDirection === 1 ?
                  (
                      mouseOnAxis < targetS1 + targetMoveDistance // over dragEl shadow
                  ) :
                  (
                      mouseOnAxis > targetS2 - targetMoveDistance
                  )
          )
          {
            return lastDirection * -1;
          }
        } else {
          invert = true;
        }
      } else {
        // Regular
        if (
            mouseOnAxis > targetS1 + (targetLength * (1 - swapThreshold) / 2) &&
            mouseOnAxis < targetS2 - (targetLength * (1 - swapThreshold) / 2)
        ) {
          return ((mouseOnAxis > targetS1 + targetLength / 2) ? -1 : 1);
        }
      }
    }

    invert = invert || invertSwap;

    if (invert) {
      // Invert of regular
      if (
          mouseOnAxis < targetS1 + (targetLength * invertedSwapThreshold / 2) ||
          mouseOnAxis > targetS2 - (targetLength * invertedSwapThreshold / 2)
      )
      {
        return ((mouseOnAxis > targetS1 + targetLength / 2) ? 1 : -1);
      }
    }

    return 0;
  }

  /**
   * Gets the direction dragEl must be swapped relative to target in order to make it
   * seem that dragEl has been "inserted" into that element's position
   * @param  {HTMLElement} target       The target whose position dragEl is being inserted at
   * @param  {Object} options           options of the parent sortable
   * @return {Number}                   Direction dragEl must be swapped
   */
  function _getInsertDirection(target, options) {
    var dragElIndex = _index(dragEl, options.draggable),
        targetIndex = _index(target, options.draggable);

    if (dragElIndex < targetIndex) {
      return 1;
    } else {
      return -1;
    }
  }


  /**
   * Generate id
   * @param   {HTMLElement} el
   * @returns {String}
   * @private
   */
  function _generateId(el) {
    var str = el.tagName + el.className + el.src + el.href + el.textContent,
        i = str.length,
        sum = 0;

    while (i--) {
      sum += str.charCodeAt(i);
    }

    return sum.toString(36);
  }

  /**
   * Returns the index of an element within its parent for a selected set of
   * elements
   * @param  {HTMLElement} el
   * @param  {selector} selector
   * @return {number}
   */
  function _index(el, selector) {
    var index = 0;

    if (!el || !el.parentNode) {
      return -1;
    }

    while (el && (el = el.previousElementSibling)) {
      if ((el.nodeName.toUpperCase() !== 'TEMPLATE') && el !== cloneEl) {
        index++;
      }
    }

    return index;
  }

  function _matches(/**HTMLElement*/el, /**String*/selector) {
    if (el) {
      try {
        if (el.matches) {
          return el.matches(selector);
        } else if (el.msMatchesSelector) {
          return el.msMatchesSelector(selector);
        } else if (el.webkitMatchesSelector) {
          return el.webkitMatchesSelector(selector);
        }
      } catch(_) {
        return false;
      }
    }

    return false;
  }

  var _throttleTimeout;
  function _throttle(callback, ms) {
    return function () {
      if (!_throttleTimeout) {
        var args = arguments,
            _this = this;

        _throttleTimeout = setTimeout(function () {
          if (args.length === 1) {
            callback.call(_this, args[0]);
          } else {
            callback.apply(_this, args);
          }

          _throttleTimeout = void 0;
        }, ms);
      }
    };
  }

  function _cancelThrottle() {
    clearTimeout(_throttleTimeout);
    _throttleTimeout = void 0;
  }

  function _extend(dst, src) {
    if (dst && src) {
      for (var key in src) {
        if (src.hasOwnProperty(key)) {
          dst[key] = src[key];
        }
      }
    }

    return dst;
  }

  function _clone(el) {
    if (Polymer && Polymer.dom) {
      return Polymer.dom(el).cloneNode(true);
    }
    else if ($) {
      return $(el).clone(true)[0];
    }
    else {
      return el.cloneNode(true);
    }
  }

  function _saveInputCheckedState(root) {
    savedInputChecked.length = 0;

    var inputs = root.getElementsByTagName('input');
    var idx = inputs.length;

    while (idx--) {
      var el = inputs[idx];
      el.checked && savedInputChecked.push(el);
    }
  }

  function _nextTick(fn) {
    return setTimeout(fn, 0);
  }

  function _cancelNextTick(id) {
    return clearTimeout(id);
  }


  /**
   * Returns the "bounding client rect" of given element
   * @param  {HTMLElement} el                The element whose boundingClientRect is wanted
   * @param  {[HTMLElement]} container       the parent the element will be placed in
   * @param  {[Boolean]} adjustForTransform  Whether the rect should compensate for parent's transform
   * (used for fixed positioning on el)
   * @return {Object}                        The boundingClientRect of el
   */
  function _getRect(el, container, adjustForTransform) {
    if (!el.getBoundingClientRect && el !== win) return;

    var elRect,
        top,
        left,
        bottom,
        right,
        height,
        width;

    if (el !== win) {
      elRect = el.getBoundingClientRect();
      top = elRect.top;
      left = elRect.left;
      bottom = elRect.bottom;
      right = elRect.right;
      height = elRect.height;
      width = elRect.width;
    } else {
      top = 0;
      left = 0;
      bottom = window.innerHeight;
      right = window.innerWidth;
      height = window.innerHeight;
      width = window.innerWidth;
    }

    if (adjustForTransform && el !== win) {
      // Adjust for translate()
      container = container || el.parentNode;

      // solves #1123 (see: https://stackoverflow.com/a/37953806/6088312)
      // Not needed on <= IE11
      if (!IE11OrLess) {
        do {
          if (container && container.getBoundingClientRect && _css(container, 'transform') !== 'none') {
            var containerRect = container.getBoundingClientRect();

            // Set relative to edges of padding box of container
            top -= containerRect.top + parseInt(_css(container, 'border-top-width'));
            left -= containerRect.left + parseInt(_css(container, 'border-left-width'));
            bottom = top + elRect.height;
            right = left + elRect.width;

            break;
          }
          /* jshint boss:true */
        } while (container = container.parentNode);
      }

      // Adjust for scale()
      var matrix = _matrix(el),
          scaleX = matrix && matrix.a,
          scaleY = matrix && matrix.d;

      if (matrix) {
        top /= scaleY;
        left /= scaleX;

        width /= scaleX;
        height /= scaleY;

        bottom = top + height;
        right = left + width;
      }
    }

    return {
      top: top,
      left: left,
      bottom: bottom,
      right: right,
      width: width,
      height: height
    };
  }


  /**
   * Checks if a side of an element is scrolled past a side of it's parents
   * @param  {HTMLElement}  el       The element who's side being scrolled out of view is in question
   * @param  {String}       side     Side of the element in question ('top', 'left', 'right', 'bottom')
   * @return {Boolean}               Whether the element is overflowing the viewport on the given side of it's parent
   */
  function _isScrolledPast(el, side) {
    var parent = _getParentAutoScrollElement(parent, true),
        elSide = _getRect(el)[side];

    /* jshint boss:true */
    while (parent) {
      var parentSide = _getRect(parent)[side],
          visible;

      if (side === 'top' || side === 'left') {
        visible = elSide >= parentSide;
      } else {
        visible = elSide <= parentSide;
      }

      if (!visible) return true;

      if (parent === win) break;

      parent = _getParentAutoScrollElement(parent, false);
    }

    return false;
  }

  // Fixed #973:
  _on(document, 'touchmove', function(evt) {
    if ((Sortable.active || awaitingDragStarted) && evt.cancelable) {
      evt.preventDefault();
    }
  });


  // Export utils
  Sortable.utils = {
    on: _on,
    off: _off,
    css: _css,
    find: _find,
    is: function (el, selector) {
      return !!_closest(el, selector, el, false);
    },
    extend: _extend,
    throttle: _throttle,
    closest: _closest,
    toggleClass: _toggleClass,
    clone: _clone,
    index: _index,
    nextTick: _nextTick,
    cancelNextTick: _cancelNextTick,
    detectDirection: _detectDirection,
    getChild: _getChild
  };


  /**
   * Create sortable instance
   * @param {HTMLElement}  el
   * @param {Object}      [options]
   */
  Sortable.create = function (el, options) {
    return new Sortable(el, options);
  };


  // Export
  Sortable.version = '1.8.3';
  return Sortable;
});